Loss of genetic variation.
Hope this helps!
-Payshence
They are like that because they can't always be faulty and may have at least some spark of truth to this theory also as stated earlier a theory in scientific terms is just an observation so it can't really be turned down hence theory.
Virus are living because they:
Reproduce, have Genetic Material (Nucleic Acids) and Adapt
.
Explanation:
Virus have genes or genetic material which are layered in a capsid or protein coat and sometimes a lipid bilayer.
It is not made up of cells yet can be considered a living organism because of the genetic material RNA or DNA in it.
The infect the host and take over host replication machinery and replicates itself. Although it is not able to replicate outside the living body.
They adapt to the host's body environment as many adaptation are present in it as capsid layer which protects its genetic material from getting degrade till the time it reaches nucleus of the cell.
There are 7 point criteria for an organism to be living, virus fulfils some of it except having made up of cells and having cellular organization.
Carbon fixation, reduction phase, carbohydrate formation, and regeneration phase.